A switched-mode power converter (also referred to as a “power converter”) is a power supply or power processing circuit that converts an input voltage waveform into a specified output voltage waveform. Alternating current to direct current (“ac-dc”) power converters convert an ac input voltage into a dc output voltage. Controllers associated with the power converters manage an operation thereof by controlling conduction periods of power switches employed therein. Generally, the controllers are coupled between an input and output of the power converter in a feedback loop configuration (also referred to as a “control loop” or “closed control loop”).
A common design requirement for a power converter is to estimate an input power accurately. Sensing and signal-conditioning circuits for a rectified sensed input voltage and current invariably produce a small, but significant dc offset (also referred to as an “offset” or a “bias”), which compromises the accuracy of an input power measurement. Calibration is a common approach for correcting dc offsets, but calibration adds a significant manufacturing cost, which is problematic in a high-volume, low-cost manufacturing environment.
Accordingly, what is needed in the art is a process for producing an accurate estimate of power in a power converter or other circuit and a related method that overcomes the deficiencies in the prior art.